Ask HN: Best ways to further my understanding of relational databases?

There are a lot of things out their to support a developer who wants to get their heads around web application development. From written tutorials, to screencasts, to interactive sites with REPL style code challenges. Looking at sites these course based sites like codeacademy, codeschool, khanacademy, udacity and coursera, I am struggling to find a well rounded course in interacting with databases. My current development position has helped my get around document driven databases and full text search engines, however, it has given me little relational database skills. What would HN recommend I do? In order to strengthen my confidence with integrating with relational databases and SQL. The aim is to be both well rounded as a full stack developer and more employable. I can understand the argument that I just have to get building these things myself. Believe me I have given it a go. But would be nice if someone else out there found a bit of relational database learning gold! Maybe you can recommend a good Coursera or Udacity course, which incorporates some of these technologies? Maybe I just need to get my teeth into a Big Data style problem?